The AEM 21-478WR Performance Cold Air Intake System produces horsepower and torque gains by replacing your vehicle’s restrictive factory air filter and air intake housing. This air intake system was designed, tuned and dyno-tested to fit specific Subaru WRX, WRX STI, Impreza WRX and Impreza WRX STI models. Air enters the system through an oversized AEM Dryflow synthetic washable air filter for outstanding air flow, filtration and performance. The air filter is located in the original air box space and is protected by a heat shield which is designed to reduce intake air temperature and increase horsepower. The intake tubing is constructed from mandrel-bent aluminum featuring a durable textured red powder coated finish. This air intake system was developed to accommodate the engine’s factory emissions control devices including the mass air flow sensor. The cylinder shaped AEM Dryflow air filter is made from an oil-free, synthetic filter media that can be used for up to 100,000 miles before cleaning is needed (depending on driving conditions). The air intake system is easy to install with commonly available tools and it is backed by AEM's Lifetime Limited Warranty. Some AEM air intakes are not legal for sale or use in California and other states adopting California emission standards while others are 50 state legal. View the 21-478WR vehicle applications to determine the legal status for each vehicle.

• Increased horsepower
• Tuned and dyno-tested to improve acceleration and engine sound
• Low restriction aluminum tubing
• Easy to install using commonly available tools
• Air filter lasts up to 100,000 miles before cleaning is required (depending on driving conditions)
• Washable and reusable oil-free filter media
• AEM Lifetime Limited Warranty

Estimated Horsepower Gain	36 HP @ 5300 RPM
Replacement Filter	21-2029DK
Air Filter Color	Red
Air Filter Material	Non-woven Synthetic
Air Filter Outlet Shape	Round
Clamps Included	3
Clamp Material	Steel
Clamp Style	Regular
Couplers Included	None
Product Style	AEM Cold Air Intake System
Air Filter Height	9.125 in (232 mm)
Intake Pipe Color / Finish	Wrinkle Red
Intake Pipe Material	Aluminum
CARB EO Number	D-670-21
Street Legal In All US States	Yes
TUV Approved (Europe)	No
Weight	7.4 lb (3.3 kg)
Air Filter Large End Diameter	6 in (152 mm)
Product Box Height	12.25 in (311 mm)
Product Box Length	20.25 in (514 mm)
Product Box Width	12.25 in (311 mm)
Mounting Hardware Included	Yes
Warranty	Limited Lifetime